Many people have considered wearing the same pair of underwear for an extra day to avoid doing laundry, but making it a habit can have unwanted effects on personal hygiene. Throughout the day, underwear absorbs sweat, body oils, dead skin cells, and naturally occurring bacteria. Wearing the same pair again means those substances remain in close contact with your skin for even longer.

Over time, repeatedly rewearing unwashed underwear can increase the likelihood of skin irritation, unpleasant odors, and certain infections. Depending on a person’s anatomy and other factors, it may also contribute to issues such as yeast infections, urinary tract infections, or fungal conditions like jock itch, particularly when moisture becomes trapped against the skin.

The type of fabric you wear also makes a difference. Cotton is generally recommended because it is breathable and helps wick away moisture, allowing better airflow throughout the day. Synthetic materials, such as polyester or nylon, tend to retain more heat and moisture, creating an environment where bacteria and fungi can thrive more easily.

Occasionally wearing the same pair for a second day—especially after minimal activity—may not always lead to problems, but it isn’t considered a good long-term practice. For better hygiene and skin health, experts generally recommend changing into a clean pair of underwear every day and choosing breathable fabrics whenever possible.